IIF function in SQL Server

we will discuss IIF function in SQL Server.

IIF function

• Introduced in SQL Server 2012
• Returns one of two the values, depending on whether the Boolean expression evaluates to true or false
• IIF is a shorthand way for writing a CASE expression

Syntax : IIF ( boolean_expression, true_value, false_value )

Example : Returns Male as the boolean expression evaluates to TRUE

DECLARE @Gender INT

SET @Gender = 1

SELECT IIF( @Gender = 1, 'Male', 'Femlae') AS Gender

Output : 


Example : Using IIF() function with table data. We will use the following Employees table for this example.


SQL Script to create Employees table

Create table Employees

(

     Id int primary key identity,

     Name nvarchar(10),

     GenderId int

)

Go

Insert into Employees values ('Mark', 1)

Insert into Employees values ('John', 1)

Insert into Employees values ('Amy', 2)

Insert into Employees values ('Ben', 1)

Insert into Employees values ('Sara', 2)

Insert into Employees values ('David', 1)

Go

Write a query to display Gender along with employee Name and GenderId. We can achieve this either by using CASE or IIF.


Using CASE statement

SELECT Name, GenderId,

        CASE WHEN GenderId = 1

                      THEN 'Male'

                      ELSE 'Female'

                   END AS Gender

FROM Employees

Using IIF function

SELECT Name, GenderId, IIF(GenderId = 1, 'Male', 'Female') AS Gender

FROM Employees